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3 A GREEN PREFAB CAN GO ANYWHERE The Glidehouse is a prototype for a new family of well-designed factory-made houses “On hot days, we keep the house cool by opening the windows and doors to create a cross-breeze. When it’s cold outside, we simply open the sunshades to let the sunlight in and warm the rooms. This alone has substantially decreased the amount of money we spend on utility bills.” —Michelle Kaufmann, architect DETAILS • Size and layout: 1566 sq. ft.; 3 bedrooms, 21 ⁄2 baths • Location: Northern California • Cost per sq. ft.: $250 • Architect: Michelle Kaufmann Designs • Builder: Cullen Woodworking (other Glidehouse models are built by various factories) irrigation systems, low-flow fixtures, and plumbing that minimizes hot-water waste. Water is precious in Frisco, Texas, a city of 88,000 located 25 miles north of Dallas. Frisco’s mandatory green-building guidelines include a number of water-conservation measures, such as a “drought-tolerant” landscaping option, mulching, and zoned irrigation systems. If a house doesn’t pass, the builder doesn’t get a certificate of occupancy. Keeping indoor air healthful and choosing “green” materials Energy-efficient houses are sealed tightly. But tightly sealed houses can trap a variety of contaminants, including the chemicals found in adhesives, carpets, furniture, and building materials. The contaminants can end up creating some pretty lousy indoor-air quality. That, in turn, can be a contributor to health problems such as asthma and allergies. As with energy conservation, improving indoor-air quality amounts to a number 68 FINE HOMEBUILDING of interconnected steps. The aim is to keep an adequate amount of fresh air coming into the house and to limit exposure to noxious chemicals. Guidelines often recommend closed com- bustion appliances, which draw combustion air from outside a building; bathrooms equipped with ventilation fans that can be operated with automatic timers or humiditysensing switches; kitchen ranges vented to the outside; and whole-house ventilation systems equipped with energy-recovery ventilation equipment that reduces energy loss. But relying on mechanical equipment to keep air moving doesn’t appeal to all green builders. Riversong, for instance, has been critical of one highly efficient house in Vermont (featured in FHB #161, pp. 74-79) because it’s “a box that is hermetically sealed so that it cannot breathe without artificial respiration.” He adds: “And, of course, artificial respiration works only when power is not disrupted, which happens with some regularity in rural Vermont.” He’d prefer designs relying on passive ventilation. Indoor-air quality can be improved by choosing building materials and furnishings that don’t off-gas volatile organic compounds (VOCs) and by keeping the garage separated from living spaces to limit exposure to autoemission toxins. Choosing building materials that either can be produced sustainably or are good for buildings and occupants is a related, and sometimes contentious, part of green building. Recycled, locally harvested, and salvaged materials all are favored, as well as simply using fewer materials to begin with (in other words, making houses only as big as they really need to be). Any discussion of green materials, how- ever, can become complicated. For example, structural insulated panels (SIPs) are effective thermal insulators, and their orientedstrand-board skins make good use of easily replenished wood. That’s good. But they are Top photo: John Swain Photography; small prefab photos: courtesy of Michelle Kaufmann Designs. Photo facing page, bottom: Paul Warchal.